; 定义月降水量数据
(def precipitation
  (list .77 1.74 .81 1.20 1.95 1.20 .47 1.43 3.37 2.20 3.00 3.09 1.51 2.10 .52 1.62 1.31 .32 .59 .81 2.81 1.87 1.18 1.35 4.75 2.48 .96 1.89 .90 2.05))

; Z-score标准化
(defun standardize (x)
  (/ (- x (mean x)) 
    (standard-deviation x)))

; 输出月平均降水量
(format t "[Mean precipitation of month: ~d]~%~%" (mean precipitation))
; 输出降水量的标准差
(format t "[Standard deviation of precipitation: ~d]~%~%" (standard-deviation precipitation))
; 月降水量数据标准化
(format t "[Precipitation standardization: ~d]~%~%" (standardize precipitation))